US2382873A - Paper screw cap - Google Patents

Description

ug. 1945 c. w. soonwm 2,332,873

PAPER SCREW CAP 4 Filed Nov. 11, 1942 '3 Sheets-Sheet 1 INVENTOR. far! [1. 60009120! I w g/m5) Aug. 14, 1945. c w GQQDwlN I 2,382,873

PAPER SCREW CAP Filed Nov. 11, 1942 3 Sheets-Sheet 2 7 INVENTQR. ("01"! Patented Aug. 14, 1945 PAPER SCREW CAP Carl W. Goodwin, North Plainfield, N .'J ass'ignor to American Seal-Kan Corporation of Delaware, Wilmington, Del., a corporation of Delaware Application November 11, 1942, Serial No. 465,194

7 Claims.

This invention relates to paper caps having an internal thread suitable for use as screw-caps for jars, bottles and the like.

An object of the invention is to provide a threaded cap made from a paper blank or the like and having integrally formed threads of a higher degree of hardness and rigidity than the remainder of the cap.

Another object is to provide a unitary cap of the above type which is formed from a paper blank by a die molding operation.

Another object is to provide a cap of the above type having integrally formed solid, hard raised threads which are seamless in cross-section as distinguished from being folded, laminated, or corrugated.

Another object is to provide a cap of the above type having outer reenforcing means to impart further rigidity thereto.

Another object is to provide a paper screw-cap having a sealing compound for eifecting an airtight seal with the lip of the bottle or jar to which it is applied.

Variou other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are characteristic of this invention are set forth more in detail in the claims appended hereto, the nature and scope of the invention may be better understood by referring to the following description, taken in connection with the accompanying drawings forming a part thereof, in which certain specific embodiments have been set forth for purposes of illustration.

In the drawings: r

Fig. 1 is a vertical section through the upper die member embodying the present invention;

Fig. 1a is a vertical section through the lower die member embodying the present invention;

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1 showing the internal die segments in contracted position;

Fig. 3 is a vertical section through'the upper and lower die members in cap forming position;

Fig. 4 is a transverse section taken on the line 4-4 of Fig. 3 showing the internal die segments in expanded position;

Figs. 5 to 8 are enlarged detail views showing successive operating positions of the forming dies;

. Fig. 9 isan inside perspective view of the finished cap;

Fig. 10 is an outside perspective View of the cap showing the. outer band being applied thereto;

Fig. 11 is a broken sectional view showing the cap applied to the mouth of a glass jar;

Fi 12 is a fragmentary plan view of the reenforcing cover;

Fig. 13 is a perspective view, partly in section, showing the cap positioned within a reenforcing shell; and y Fig. 14 is a perspective View partly in section showing a modified form of cap having an internal'sealing compound for sealing the cap onto a bottle or jar. r I

In the following description and in the claims certain specific terms are used for conveniencein referring to the various details of the invention. These terms, however, are to be interpreted as broadly as the state of the art will permit,

In accordance with the present invention, the solid, raised threads of a high degree of hardness and rigidity are produced by die-forming a retreated paper blank under high'pressure. An essential characteristic resides in so pretreating the blanks that under the high pressures employed in die-forming, the fibers of the paper are broken down or re-arranged and are compactedand interfelted together to form a paper having a differ-- ent cross-section than the blank and which consists of one solid, seamless, uniform, homogeneous layer as distinguished from folded or laminated layers which would be produced by merelyfolding the blank upon itself without causing a rearrangement of the fibers within the material.- The process may be considered to constitute paper welding because the original contour lines and surfaces are destroyed and a homogeneous section is produced which may be of a shape and thickness diifering from that of the original blank. In addition, the high pressure used in dieforming compacts the fibers to greatly increase the density and hardness of the paper. The threads may thus be made harder than the remainder of the cap. This is an important feature since the threads are relied upon for holding the cap inposition and are subjected to the greatest stress.

The paper stock must be specially pretreated to condition the same for the die-forming oper-. ation. This pretreatment comprises impregnating the paper with a composition with softens the fibers for forming but sets as a binder or stiffener for holding the fibers permanently in formed position and imparts'increated rigidity thereto. A The paper may, for example, be imafiin .waxhaving incorporated therein a-small" amount of a hardening wax, such as carnauba or montan as set forth in Baum Patent No. 1,668,-

349, dated May 1, 1928. Moisture may be used if desired to assist in softening the fibers. Other binder, hardening or water-proofing compositions may also be used.

After the pre-treatment the paper is preferably allowed to stand for a substantial period of time such, for example, as twenty-four hours, in a closed container for seasoning and tempering.

It is then in condition for the die-forming oper ation.

A die for forming internally threaded paper covers for glass jars or the like is shown in Figs.; 1 to 8. Referring first to Fig. la, the lower die is shown as comprising a base I having an axial bore through which a plunger 2 extends. The base carries an outer ring member 3 in which is secured, by means of screws 4, a stationary.

forming ring 5 which constitutes the outer forming member. The ring 5 is provided with an inner peripheral surface 6 defining the outer peripheral surface of the cap skirt and an annular part! to form the outer portion of the cap diaphragm. Thesurface' 6 may be rounded as at 6a to prevent injuring the paper as it is drawn thereover.

The plunger 2 carries a head 8 having a surface}! which, in its upper position, is flush with the top surface 10 of the members 3 and 5Ias shown'in Fig. 1a and in its lower position is flush with the surface I of the ring 5 as shown in Fig. 3. Thelplunger 2 is provided with a flange II which engages the base to limit its movement. A spring I2, seated in a bore |3 in the base I, bears against the head 8 and serves to hold the same normally in its upper position as shown in Fig. 1a... The inner surfacesfi and l of the ring 5 and the top surface 9 of the head 8 conform to the outer surface of the finished cap.

The upper die is shown in Fig. 1 as comprising a housing in which a liner 2| and a spring 22 are seated. The liner 2| and the spring 22 are held in positionby a cover 23 which is secured by screws 24. The spring 22 bears against the surface 25 of a cup 26 having a ring 21 which extends through an vopening in the end 28 of the housing 20 and having a flange 29 which is slidablexwithin the liner 2|. The end 28 of the housing 20 engages the flange 29 to limit the movement of the cup 26.

.The housing 20 carries. a retaining ring 20 which is threaded thereon and in which a pressure ring 3| is positioned. This pressure ring 3| is fixedin the retaining ring 3|] by means of a spacer 32. A head 33 is slidably mounted within the retaining ring and carries a lip 34 which slides within the spacer 32 and engages a shoulder 35 on the pressure ring 3| for limiting the movement 'of the head 33.

A pin 40 is slidablymounted within thehead 33 and is provided with a bottom flange 4| having a surface 42 conforming to the centralportion of the inner surface of the diaphragm of the cap. A plurality of segmental members 45 are mounted for. radial sliding movement on the flange 4| and are normally held in their inner position by means of tension'springs 46. These segmental members 45 are provided with bottom annular surfaces 41 which conform to the outer portion. of the'inner surface of the diaphragm oft-the, cap and with peripheral surfaces 48 which formed in the surfaces 48 to conform to the desired raised beads on the inner surface of the cap flange. The segmental members 45 are provided with shoulders 50 which are held against the flange 4| by means of a ring 5| bearing against the top surfaces of the members 45 and held downwardly by springs 52 seated in recesses in the ring 5| and the head 33.

The springs 52, through the ring 5|, members 45 and flange 4|, also serve to hold the pin 40 in its lower position. The pin 40 is attached to a top flange member 53 which slides in cooperating bores in the cup 26 and in the head 33 and limits the relative movement of the pin 40 with respect thereto. The head 33 is provided with a conical end surface 54 which engages cooperating surfaces 55 on the members 45 to cam the same outwardly.

The operation of the die is as follows. The springs 52 normally hold the segmental members 45 and the post 40 in their lower position in which the members 45 are retracted by means of thetension springs 46 and the spring I2 holds head. 8 of the lower. diein its upper position as shown in Fig. la. A blank 60 is now positioned betweenthe dies and the dies are brought'together by either raising the lower die or lowering the upper die. As the diesapproach, the surfaces 42 and 41 of the flange 4| and of the segmental members 45 respectively first engage the top of the blank 60. The relationship between the various springs is such that on continued downward movement of the upper die the springs 52 are compressed, thus lowering the head 33 with respect to the segmental members 45 whereby the tapered surfaces 54 and 55 serve to expand the segmental members 45 against the tension of the springs 46 into the position shown in Fig. 5. The parts of the upper die now remain in the same relative positions while the flange 4| and the segmental members 45 press the head 8 down.. wardly against the. tension of the spring l2.

When the head 8 reaches the limit of its move-.

ment. with the bottom surface thereof engaging the surface of the base the top surface 9 isin line with the annular surface I of the ring 5 as shown in Fig. 6. 7 This operation serves to cup the blank to form a diaphragm 62 and an upstandingmarginal flange or skirt 63. The inner peripheral surface 6 of the ring 5 and the outer peripheral surfaces 48 of the segmental members 45 now define the contour of the finished marginal flange of the cap. The spacing between the surfacest and 48 is shown as greater than the thickness of the blank so that the flange 63 rests loosely therein as shown in Fig. 6. Of course, if the flange of the cap is to be made of the same thickness-as the blank, the surfaces 6 and 48 would'be-correspondingly spaced and the flange 63 would be snugly held thereby. g

. Furt er downward movement of the housing 20 compresses the sprin 22 and permits the pressure ring 3| to move downwardly into the space between the cooperating surfaces 6 and 43 first torearrange the fibers tqfill in the mold cavity as indicatedin Fig. '7 andthen to compact the same to a hard, dense structure as shown in Fig. 8. 'During this stage of theoperation the fibers. are forced into the depressed threads 49 of the members 45 to formraised. threads 65 on the flange 64 of the formed cap. The entire flange,

64, including, the raised threads 65, is morehighly compacted and is thus harder and denser: than thediaphragm 66v of. the cap which has about the consistency of the originallblank. It is to beparticularly noted that the threads and marginal flange are seamless, solid and homogeneous as distinguished from being folded or laminated and have the characteristics of having been die-compressed from a pretreated, waxed blank.

When the die members are separated the reverse operation takes place, the pressure ring 3| first being raised, the cap lifted out of the lower die on the upper die and the segmental members 45 being retracted to release the formed cap.

The formed cap, as shown in perspective in Fig. 9, is suitable for use without further treatment. In many cases, however, it is desirable to apply printing to the top for purposes of ornamentation or advertising. Such printing is preferably done on a thin paper cover which is secured by a suitable adhesive to the outer surface of the diaphragm 66 of the cap. For strengthening purposes, the cover 10 may be provided with tabs H which extend downwardly and are secured around the outside of the upstanding flange 64. These tabs may be contiguous to substantially completely cover the outside of the skirt. In order to provide a more finished appearance, and also to provide a further strengthening means for opposing the force which tends to cause the flange to spread outwardly when the cap is screwed tightly onto a bottle, a band of strengthening material such as tape or heavy paper 12 may then be wound around the outer surface of the flange 64 over the tabs H. The cap thus produced is sufliciently strong for most uses and has a pleasing finished appearance.

In certain instances the caps may be used as a liner for a rigid outer shell 80 as shown in Fig. 13. The outer shell may, for example, be made of glass or other moldable material which is readily formed into cupped shape with a top 8| and a downwardly extending flange 82. This assembly may be made to possess the strength of a metal cap and may be used in many instances as a replacement therefor. The paper liner may be held in the shell by friction or may be adhesively secured therein as required.

According to a further embodiment of the invention, it is sometimes desirable to provide an air-tight seal between the top of the jar or bottle and the inner surface of the cap. This may be accomplished as illustrated in Fig. 14 by recessing, if desired, a portion of the rim of the diaphragm 66 and inserting therein a sealing compound, preferably a compound having adhesive characteristics at room temperatures, such as animal glue or plasticized thermoplastic materials, for example, ethyl cellulose compounds or vinyl resins or the like. In certain instances a thermoplastic material may be employed which must be heated to an elevated temperature for sealing purposes. This may be desirable in cases where the seal must be maintained a long period of time.

The cap may include the usual disc liner of treated paper or other material according to the contents of the container. This liner effects a seal with the container lip and prevents the contents from coming into contact with the cap itself.

It is to be understood that the above examples are only'illustrative and that various changes and modifications may be made therein and that the invention is capable of various uses which will be readily understood by a person skilled in the art.

What is claimed is:

1. A paper screw-cap comprising a central diaphragm portion and an upstanding annular skirt, said skirt having solid, raised screw threads formed integrally on one face thereof, the opposite face being substantially smooth, the paper in said skirt and threads containing a binder and being in a solid, homogeneous, seamless, interfelted condition, said skirt and threads being denser than the remainder of the cap and having a higher degree of hardness.

2. A paper screw-cap comprising a diaphragm portion and an upstanding annular skirt, said skirt being thicker than said diaphragm portion and having solid, raised screw thread formed integrally thereon, the paper in said skirt containing a binder and being in a solid, homogeneous, seamless, interfelted condition, said skirt and threads being denser than the remainder of the cap and having a higher degree of hardness.

3. A paper screw-cap comprising a diaphragm portion and an upstanding annular skirt, said skirt being thicker than said diaphragm portion and having solid, raised screw threads formed integrally on the inner peripheral surface thereof and having a smooth, outer surface,the paper in said skirt containing a binder compound and being in a solid, homogeneous, seamless, interfelted condition, said skirt and threads being denser than the remainder of the cap and having a higher degree of hardness.

4. In a paper screw-cap as set forth in claim 1, a reenforcing band secured around the outside of said skirt to increase the rigidity thereof.

5. In a paper screw-cap as set forth in claim 1, a cover having peripheral tabs extending doWn-, wardly over the outside of said skirt and adhesively secured thereto, said tabs being contiguous and substantially .covering the entire skirt, and a reenforcing band secured around the outside of said skirt over said tabs to increase the rigidity thereof.

6. In a paper screw-cap as set forth in claim 1, an annularband of adhesive material on the inner surface of said diaphragm to engage and seal against the lip of a container.

7. A paper screw-cap as set forth in claim 1 having an outer shell of rigid material covering the entire outer surface of said diaphragm and skirt to impart a rigidity simulating that of a metal cap.

CARL W. GOODWIN.

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